Brake



Nov. 22, 1938. E.\G. CARROLL 2,137,525

BRAKE l Orlginal Filed April 15, 1932 2 Sheets-Sheet 1 INVENToR.

faune- G. C'nmou.

IBYWML.

ATTORNEY.

Nov. 22, 1938. E. G. CARROLL Y 2,137,525

BRAKE Original Filed April 13, 1932 2 Sheets-Sheet 2 v y /la TIG. l 64 y /65 /79 I BY @H5675 Patented Nov. 22, 1938 UNITED STATES PATENT OFFICE v BRAKE Original application April 13, 1932, Serial No. 605,083, now Patent No. 2,074,719. Divided and this application 23,425

8 Claims.

This invention relates to brakes and more especially to hydraulic operating systems therefor.

One of the objects of my invention is to provide 5 improved means for developing and maintaining a superatmospheric pressure acting upon the liquid in a hydraulic brake system so as to keep the operating part of the system full of liquid at all times and to eliminate the springy pedal 10 accompanying the presence of air mixed with the liquid in said operating part of the system.

A further object of the invention is to provide improved means for preventing the ingress of air into the operating parts of the system and l5 especially into the wheel cylinders thereof.

Further objects of the invention will be apparent after a reading of the subjoined specification and claims and after a consideration of the attached drawings in which:

Figure 1 is a view showing, more or less diagrammatically, parts of a hydraulic braking system including a master cylinder, a wheel cylinder, and connections between the master cylinder and the wheel cylinder;

Figure 2 is a View showing a modied form of master cylinder adapted to be substituted for the master cylinder shown in Figure 1; and

'Figure 3 is a View showing another modified form of master cylinder also adapted to be sub- 30 stituted for the master cylinder shown in Figure 1.

The brake system shown in Figure-1 comprises a reservoir 89, a master cylinder 90, and wheel cylinder 9|. The reservoir 89 is provided with 3,', a partition 92, a cover 93, and a liquid level -indicator 94. It has outlet openings 95 and 96 which are connected to the master cylinder 92.

The master cylinder 90 has a plunger 91 provided with a plurality of annular sealing cups 4U such as 98, 99 and IIlI, the rst named facing forward and the last two named being reversed relative to each other and positioned toward the rear. By reason of these cups, fluid is prevented from leaving or entering the cylinder except through openings |02 and I 03 which are connected with the openings 95 and 9E respectively of reservoir 89 or through openings |04' and |05 connected with the front and rear brakes lrespectively.

The plunger S1 slides through a head |06 which is secured within the cylinder 90 so as to be allowed a limited longitudinal movement therein, the head being provided with ports such as |07, |08, and |09 communicating with the opening f :'01A i?, envar-dlg: of the head |06, there is May 25, 1935, Serial No.

(Cl. (iO-54.6)

provided an annular packing cup I I which faces rearwardly and is held in position by a tubular member I I I which may be formed if desired by a short section of pipe. Forward of the head |06 there is provided a similar packing cup I I2 which faces forwardly and is heldin position by a similar tubular member .I I3. It is to be noted that the length of members III and H3 as Well as the groove in which the head |06 is seated allow a slight longitudinal movement of the head |06 and with it, the cups |09 and ||2 so as to allow equalizing of pressure between the front and rear brakes.

The wheel cylinder 9| is provided with an annular boss or projection I I4 corresponding to the projection 62. However, a tubular member II5 is provided for holding the cups IIB and III in position when the fluid in the cylinder is not under brake applying pressure. It is to be understood that when operating pressure is applied to the fluid, the fluid itself maintains the cups in their position. The plungers are also provided with additional packing cups IIla and IIIa smaller in area and facing outward. The projection I|4 is internally threaded as at I|8 and has screwed therein a plug I I9 formed with a'conical end adapted to seat in a conical shaped valve seat concentric with the projection IIll. The plug I I9 is itself formed with a tapped opening |20 and with intersecting bores I2I and |22.

` A bleeding hose |23 provided with a check valve I 24 is adapted to be threaded into the tapped opening |20 for the bleeding operation, the plug IIB being adapted to be loosened for the same operation.

In the operation of the braking system shown in Figure 1, pressure applied by the pedal is adapted to move the plunger 91 forward, thus imy mediately closing the port leading to the opening |03 and forcing fluid through the outlet opening |04 to the front brakes and through the outlet opening |05 to the rear brakes. The displaced uid creates pressure in the wheel cylinders and forces the plungers in the wheel cylinders apart for applying the brakes. Slight movement of the head |06 is normally effective to equalize the pressure between the front system and the rear system. However, should a leak develop in either the connections leading to the front brakes, or in the connections leading to the rear brakes, the head |05 will move to its limit of travel and the other system of brakes (rear or front) will be unaffected by the leak. X

In the bleeding operation the plugI 8 is backed off slightly from its seat and the bleeding hose |23 is attached. Then liquid is forced to the wheel cylinders by movement of the piston and is thence forced out past the check valve |24 carrying with it any air which may be trapped in the system. On the return stroke, thercheck valve |24 prevents air from returning into the wheel cylinder and additional liquid is drawn into the master cylinder through the opening |02 and then through the bores |01, |08, and |09 and past the cups |0 and |21. Should an excess of pressure be developed in the system, the pressure may be relieved through openings |03 and ||4 when the parts are in the'brake-off position. It is to be understood that during the bleeding operation, the plug |8 is backed off slightly from its seat.

In Figure 2 I have shown a modified form of cylinder somewhat similar to that shown in Figure 1, but diiering in certain details therefrom. The master cylinder 3| has formed integrally therewith a covered annular flange |32 which serves as a combined reservoir and pressure chamber for supercharging the system. Positioned in the ange |32 is an inverted container |33 formed with a flange |34. The container is normallyv urged downward into contact with an annular packing plate |35 by means of a compression spring |36 which at its lower end bears upon the flange |34 and at its upper end bears against the cover |31 for the flange |32. The cylinder 3| is also provided with two other smaller annular flanges |38 and |38, neither concentric with the flange |32. In the well formed by the flanges |38 there is positioned an annular sealing cup |30 having an L-cross section. The cup |39 covers ports |40 and |4| which allows liquid to flow into the interior of the container |33 from the ports |40 and |4| but prevents liquid from passing out through the ports |40 and |4| from the interior of the container |33. The port I4| leads to a chamber |42 formed between a shoulder |43 provided in the cylinder 3| and a head or piston |44 formed at the rear of the plunger |45, the port |40 normally leading forward of that chamber. Coacting with the head |44 is an annular sealing cup |46 which prevents the passage of fluid rearward past the head. The plunger |45 is also formed with a forward head |41 provided with a sealing cup |48, the head and the cup forming a piston and being normally positioned just rearwardly of the port |40 and forwardly of the point at which the port |4| connects with the chamber |42. When the plunger is operated, however, the piston is moved forward past the port |40. The chamber |42 is also provided with an opening |49 connected through the well formed by the flange |38a with the reservoir |32 outside of a container |33, the reservoir outside of the container being vented to the atmosphere. Associated with the opening |49 is a check valve |5| seated in the ange |38a, the valve allowing liquid to flow in from the reservoir |32 to the chamber |42 but preventing liquid from passing from the chamber to the reservoir.

The cylinder |3| is provided with an equalizing head |52 corresponding substantially with the head |06 and with cups |53 and |54 corresponding substantially to the cups 2 and ||0. The cup |53, however, is normally maintained upon its seat by means of a spring |55 which also normally urges the head |52 toward its rearward position. Liquid is supplied to the passageways formed in the head |52 through a diagonal port |56 which leads to the interior of the container |33.

Before operation of this form of master cyl` inder, liquid is poured into the reservoir |32. Operation of the plunger |45 forces air trapped in the cylinders through the openings |51 and |58 to the forward and rear brakes respectively and out of the wheel cylinder past a check valve such as one of the check valves 63 or |24. On the rearward stroke, liquid is drawn into the chamber |42 past the check valve |5|. Subsequent forward strokes force the liquid drawn into chamber 42 through port |4| into the container |33 and thence through the port |56 past the cups |53 and |54 to the forward brake system and the rear brake system. After the system has been lled with liquid, slight losses of liquid from the forward brake system may be compensated for by passage of liquid forward past the cup |48 as well as by passage of liquid rearward past the cup |54. Losses of liquid in the rear brake system is compensated by passage of liquid past the cup |53. Repeated operations of the plunger serves to supercharge the pressure by drawing in liquid past the valve |5| and forcing it through the port |4| yinto the container |33 and to the top of said container until the pressure therein reaches the weight of the spring |36 whereupon the pressure in the container |33 may be relieved back to the main part of the reservoir 32 by lifting the container off of the packing |35.

The modified form of master cylinder shown in Figure 3 is very similar to that shown in Figure 2 but is considerably simpler and cheaper to construct inasmuch as no arrangements are provided for separate systems for the front and rear brakes. Therein the cylinder |6| has a plunger |62 which corresponds substantially to the plunger |45, a reservoir |63 which corresponds substantially to the reservoir |32, and a container |64 which corresponds. substantially to the container |33. The check valve |65 corresponds substantially to the check valve |5|, and the cups |66, |61, |68 correspond substantially to the cups |45, |48 and |54. A port |69 corresponding to the port |56 leads to an annular recess |1| which corresponds substantially to the recess for the equalizing head |52. However, an annular flanged packing |12 which has an L-shape in cross section fullls the functions of the annular packing |34 and also fulfills part of the functions of the cup |39 in serving as a oneway check valve for the port |13. The port |14 is closed only when covered by the cup |61. An outlet port |15 at the forward end of the cylinder is located in the center of the cup |68 and leads to all of the wheel cylinders of the front and rear brakes.

The operation of this form of my device is substantially the same as that shown in Figure 2, with the exception that no provision is made for keeping the front brake system separate from the rear brake system.

This application is a division of my copending application Serial No. 605,083, led April 13, 1932 upon which Patent Number 2,074,719 has been issued.

It is to be understood that the above described embodiments of my invention are for the purpose of illustration only and various changes may be made therein without departing from the spirit and scope of the invention.

I claim:

1. In a hydraulic brake system a. master cylinder, a reservoir associated with said master cylinder, an inverted container positioned in said reservoir, a spring bearing upon said inverted container, and means for forcing fluid into said container to supercharge the pressure in said system.

2. In a hydraulic brake system a master cylinder, a reservoir associated with said master cylinder, an inverted container positioned in said reservoir, a spring bearing upon said inverted container, means for forcing iiuid into said container to supercharge the pressure in said system, a master piston in said cylinder, and a check valve interposed between said container and said master cylinder.

3. In a hydraulic brake system a master cylinder, a reservoir associated with said master cylinder, an inverted container positioned in said reservoir and dividing the reservoir into two portions, means for forcing iiuid into said inverted container for supercharging the pressure of liquid therein, and means for venting the other portion of said reservoir for maintaining the liquid therein under atmospheric pressure.

4. Ina hydraulic brake system a master cylinder formed with a pair of ports, a plunger positioned in said master cylinder and having a piston head normally maintained between said ports but moving in its operation to a position in advance of both ports, a reservoir associated with said cylinder, and an annular cup packing of L-shaped cross section positioned in said reservoir and ,covering both of said ports, whereby the packing serves as a one-way check valve for both of said passages.

- 5. In a hydraulic brake system a reservoir for hydraulic fluid, means for dividing the reservoir into two portions, one of which is maintained under atmospheric pressure and the other of which is maintained under supercharged pressure, resilient means in said other portion for maintaining said supercharged pressure, means for discharging fluid into said other portion upon operation of the braking system and means for discharging fluid. from said other portion into said rst portion when a. certain pressure is exceeded.

6. In a hydraulic brake system a master cylinder, a. reservoir associated with said master cylinder and having a well formed in the bottom thereof, an annular packing of L-shaped cross section positioned in said well, and a connection leading from said well to said master cylinder said packing covering the opening to said connection and acting as a check valve therefor.

7. In a. hydraulic brake system, a reservoir for hydraulic fiuid, means for dividing the reservoir into two portions, resilient means comprising trapped air for maintaining a supercharged pressure on the uid in one of said portions, an atmospheric vent in the other portion, means for discharging fluid into said one portion upon operation of the braking system, and means for discharging fluid from said one portion into the other portion when a certain pressure is exceeded.

8. In a hydraulic brake system, a reservoir for hydraulic uid, means for dividing the reservoir into two portions, resilient means comprising trapped air for maintaining a supercharged pressure on the iiuid in one of said portions, an atmospheric vent in the other portion, means for discharging fluid into said one portion upon operation of the braking system, and means for discharging fluid from said one portion into the other portion when a certain pressure is exceeded, said last-named means being below the liquid level in said one portion.

EUGENE G. CARROLL. 

